Complex heavy metal salts



United States Patent CONIPLEX HEAVY METAL SALTS Walter Reppe, Ludwigshafen (Rhine), Herbert Friederich, Worms, and Hans Lautenschlager, Ludwigshafen (Rhine), Germany, assignors to Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen (Rhine), Germany No Drawing. Application July 14, 1955 Serial No. 522,183

Claims priority, application Germany July 15, 1954 14 Claims. (Cl. 260-3265) This invention relates to complex heavy metal $3118 and to a method of manufacturing such salts. More particularly, the invention concerns. complex salts of iron, cobalt, nickel or copper With carboxylic acid. amides.

An important object of this invention is to provide new complex compounds of heavy metals and a method of producing these complex compounds.

Another object is to provide complex compounds by the interaction of iron, cobalt, nickel or copper salts with a substituted carboxylic acid amide bearing at least one organic substituent on the nitrogen atom of the amido group.

Other objects will be apparent from the more detailed description of the invention.

These objects are accomplished according to this in vention by reacting a salt, preferably a halogenide of iron, cobalt, nickel or copper, with a substituted carboxylic acid amide.

The carboxylic acid amide should contain at least one organic substituent, preferably a hydrocarbon radical, on the nitrogen atom of the amido group. Suitable carboxylic acid amides derive from primary and secondary aliphatic, cycloaliphatic, heterocyclic and aromatic amines and from aliphatic, cycloaliphatic, aromatic or heterocyclic carboxylic acids. Such carboxylic acid amides are, for instance, dimethylformamide, N-methylacetamide, N-ethylbenzoic acid amide, propionic acid pyrrolidide and'N-methylacetanilide. Other suitable carboxylic acid amides are the lactams of aminocarboxylic acids and their N-alkyl derivatives, such as pyrrolidone-Z, N-methyl'pyrrolidone-Z, caprolactam, di'methyl'acetamide, dimethylbenzamide, N-formylhexamethylene imine, N- formylpyrrolidine, di-n-dodecylpropionamide, dimethylpalmitinamide, distearylacetamide, cyclohexane carboxylic acid dimethylamide and- N-cyclohexylacetamide. The amides chiefly used are dimethyl formamide, dimethyh acetamide, pyrrolidone and N-methylpyrrolidone. The length of the chain of the; carboxylic: acids and. the amines. shall. be from 1 to 20 C-atoms, as for example with distearylacetamide or dimeth-ylpalmitine amide. oi the aliphatic, cycloaliphatic and heterocyclic compounds used should be saturated. As heavy metal salts the. bromides and iodides of iron, cobalt, nickel and copper are preferably used. Acetates, propionates'or acryl'ates of nickel or cobaltmay also be used.

The complex compounds are easily formed by mixing the initial materials and slightly heating this mixture, preferably to a temperature between 40 C. and 1 60" C. The reaction may be. carried out in the presence of a solvent, such as tetrahydrofurane, methanol, ethanol or butanol, or while an excess of the carboxylic acid amide is used. A deep green or'a blue'soluti'onor melt is soon formed thereby, from which the complex compounds separate in crystalline form when the solution or the melt is cooled. In some cases it is advantageous to add the metal salts to the acid amides in the form of aqueous solutions and to distill off the water afterwards in vacuo or azeotropically. If an excess of the carboxylic acid amide is used and the complex compound formed is soluble in the carboxylic acid amide, it is possible to separate the complex compound by the addition of liquids having a poor dissolving power for the complex compounds, for instance, by the addition of ethers, esters or hydrocarbons. The complex compounds may also be separated and/ or purified by extracting the melt or the solution and/or by recrystallization. As a rule, for 1' mole of the metal salt from 3 to 10 moles of the carboxylic acid amide are used.

The new complex compounds are usually crystalline, stable compounds having a definite melting point. They contain as a rule for one molecule of the metal salt from 3 to 8 molecules of the carboxylic acid amide.

The new complex compoundsmay be characterized by the following general formula In this formula Me is iron, cobalt, nickel or copper, these metals having an atomic number from 26 to 29; Hal is a halogen, x is an integer from 2 to 3, corresponding to the valence of the metal Me, is an integer from 3 to 8 and A is a carboxylic acid' amide containing at the nitrogen atom of the amido group at least one organic substituent which is preferably a hydrocarbon radical. The term hydrocarbon radical includes alkyl radicals, such. as methyl, ethyl, propyl or butyl, as well as alkylene radicals occurring in lactams between the amido and the oxo group.

Complex compounds containing water of crystallization separate occasionally from solutions containing water. Most of them can, however, be converted into Water-free complex compounds by recrystallization from water-free solvents, such as water-free tetrahydrofurane.

The complex compounds are, as a rule, soluble in water and inseveral organic solvents, such as alcohols, acetone, chloroform and tetrahydrofurane. The solutions of these compounds are usually stable, but sometimes when they are heated the complex compounds decompose and the simple metal salt precipitates. If the complex compounds are heated under reduced pressure to a temperature above their melting point, they often decompose and the carboxylic acid amide distills' off while the metal salts remain behind.

While the new complex compounds are easily soluble in difierent solvents, they may be used with advantage to carry out chemical reactions such as carbonylations where the difficultly soluble simple metal salts do not give a satisfactory result. The complex acid amides of nickel bromide have an excellent catalyzing action in the synthesis of acrylic acid or the derivatives thereof at raised temperature and increased pressure. The complex cobalt halides are eflicient catalysts in the carbonylation of methanol into acetic acid or the carbonylation of amines, especially tertiary amines, into amides under similar conditions. In. these cases, the presence of organic solvents is prohibitive of the use of the simple heavy metal salts. Moreover the. catalytic activity of the complex compounds are farsuperior to that of the simple salts.

The invention is further illustrated but not limited by the following examples in which the quantities are givenin parts by weight unless otherwise indicated.

Example I 20 parts of nickel-II-hromide are dissolved in 40 parts of N-methyl pyrrolidone-Z while stirring and slowly heating the mixture to a temperature of C. After the nickel bromide has completely dissolved, the solution is cooled, and. 20 parts. of a crystalline dark blue; complex compound separate. The crystal sludge is separated from p the mother liquor and the latter is covered with a layer of 80 parts of diethyl ether. Within 24 hours, 18 additional parts of the same complex compound separate. After recrystallization from tetrahydrofurane, the complex compound has a melting point of 105 C. It contains for one molecule of nickel-II-bromide three molecules of N-methyl pyrrolidone-2.

Example II Example III 2 parts of nickel bromide are dissolved in 90 parts of pyrrolidone-2 at a temperature of 120 C. The hot solution has a bluish-green color which changes when the solution is cooled to room temperature, to dark green. During cooling. 7.5 parts of a green complex salt NiBr .8- (pyrrolidone-2) crystallizes. The complex salt is washed with ether and dried under vacuum. It melts at 125 C. When heated in tetrahydrofurane, the complex compound loses part of the pyrrolidone and converts into a blue compound NiBr .3 (pyrrolidone-2) which is insoluble in tetrahydrofurane in the cold and has a melting point of 155 C.

Example IV 32.6 parts of cobalt bromide hexahydrate are dissolved while heating to 125 C. in 80 parts of pyrrolidone-2. From this solution, 52 parts of a reddish-violet complex compound CoBr .3(pyrrolidone-2) (melting point 125 C.) crystallizes after the solution has been cooled and kept for 24 hours. By the addition of ether to the mother liquor, 30 additional parts of the same complex compound can be isolated.

Example V Exmple VI A solution of parts of cupric bromide in 100 parts of dimethylformamide is evaporated at room temperature under a reduced pressure of 0.6 millimeter Hg to dryness. 18 parts of a black crystalline mass are obtained which is twice digested with 80 parts of water-free ether and dried under vacuum, whereby brilliant black crystals of a complex compound of the composition CuBr,.4- dimethylformamide and having a melting point of 76 C. to 78 C. are obtained. They dissolve easily inwater, alcohols, tetrahydrofurane or pyrridine. The complex compound is difliculty soluble in benzene and insoluble in ether, petroleum ether and ethyl acetate.

Example VII 4 150 C. From the dark blue solution, 28 parts of a dark green complex compound separate when it is cooled. The crystals are filtered ofi, washed with N- methyl pyrrolidone-2, absolute ether and dried under vacuum. The complex compound which has the composition NiCl .3N-methylpyrrolidone-Z melts at 79 C. to 80 C.

Example VIII 10 parts of nickel iodide are dissolved while heating to 100 C. in 100 parts of dimethylformamide. The obtained brown solution is filtered and evaporated under a reduced pressure of 0.5 millimeter Hg at room temperature (about C.) to dryness. 16.5 parts of a brownish-green residue remain behind. By washing this residue with tetrahydrofurane, green crystals of a complex compound of the composition NiI .5-dimethylformamide are obtained which melt after drying under vacuum at 88 C. to 90 C.

Example IX 11.3 parts of caprolactam are dissolved in 30 parts of tetrahydrofurane. To this solution 3.6 parts of finely pulverized nickel bromide are added and the mixture is then boiled for 5 hours under reflux. After cooling 12.0 parts of a yellow residuum are separated. By recrystallizing this from a large quantity of tetrahydrofurane pale yellow crystals are obtained which melt at 121 C. and correspond to the formula NiBr .4 caprolactam.

Example X 15 parts of nickel bromide are dissolved in parts of dimethylacetamide while heating. By combining the dark blue solution with 100 parts of dry ether 31 parts of a blue-green crystalline precipitate are obtained. After washing the precipitate with dry ether and drying it in vacuo it melts at 82 C. Its constitution corresponds to the formula NiBr .3 dimethylacetamide.

Example XI To a melt of 100 parts of N-methylacetanilide 21.8 parts of nickel bromide are added at 120 C. while stirring and the mixture is cooled down after an hour. The

dark green crystal mass is triturated three times with 200 parts of dry ether. The bottoms left are parts of a blue-green compound having the formula NiBr .3'N- methylacetanilide and melting at 128 C.

The invention is hereby claimed as follows:

1. A complex heavy metal salt of the general formula MeHal yA wherein Me is a metal with an atomic number from 26 to 29, Hal is a halogen, x is an integer from 2 to 3, y is in 50 parts of N-methyl pyrrolidone-2 while heated to an integer from 3 to 8 and A is a carboxylic acid amide of the formula RCONR R wherein R constitutes a radical selected from the group consisting of hydrogen, alkyl, cyloalkyl, aryl hydrocarbon, and radicals which together with R, constitute a bivalent alkylene radical, R constitutes a radical selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl hydrocarbon, and radicals which together with R, constitute a bivalent alkylene radical, and R, constitutes a radical selected from the group consisting of alkyl, cycloalkyl, aryl hydrocarbon, radicals which together with R constitute a bivalent alkylene radical, and radicals which together with R constitute a bivalent alkylene radical.

2. A complex heavy metal salt of the formula 3. A complex heavy metal salt of the formula CH,-CH:

NtBna J l O CH:

4. A complex heavy metal salt of the formula 5. A complex heavy metal salt of the formula C z-C NiBrz.3 I

6. A process of manufacturing a complex heavy metal salt which comprises reacting one mol of a halide of a metal having an atomic number from 26 to 29 with 3 to 8 mols of a carboxylic acid amide of the formula R--C0NR R wherein R constitutes a radical selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl hydrocarbon, and radicals which together with R constitute a bivalent alkylene radical, R constitutes a radical selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl hydrocarbon, and radicals which together with R constitute a bivalent alkylene radical, and R constitutes a radical selected from the group consisting of alkyl, cycloalkyl, aryl hydrocarbon, radicals which together with R constitiute a bivalent alkylene radical, and radicals which together with R constitute a bivalent alkylene radical.

7. A complex heavy metal compound comprising one molecule of a halide salt of a metal having an atomic number from 26-29, inclusive, in complex combination with 3-8 molecules of dimethylformamide.

8. A complex heavy metal compound comprising one molecule of a halide salt of a metal having an atomic number from 26-29, inclusive, in complex combination with 3-8 molecules of pyrrolidone-2.

9. A complex heavy metal compound comprising one molecule of a halide salt of a metal having an atomic number from 26-29, inclusive, in complex combination with 3-8 molecules of N-methylpyrrolidone-Z.

10. A complex heavy metal salt of the formula FeCl .3 HCON(CH 11. A complex heavy metal salt of the formula CuCl A HCON(CH 12. A complex heavy metal salt of the formula NiI .5 HC0N(CH 13. A complex heavy metal salt of the formula NiBr .3 CH .CON(CH 14. A complex heavy metal salt of the formula CHI-0H, NlGl;.3 30 CH:

N la.

References Cited in the file of this patent UNITED STATES PATENTS Carr Jan. 8, 1952 OTHER REFERENCES 

1. A COMPLEX HEAVY METAL SALT OF THE GENERAL FORMULA 